It is proposed to improve decision making in radiotherapy of cancer patients by the development of a computerized data bank and patient matching programs. These programs will match a given new patient as closely as possible with an dealized hypothetical protocol patient and/or with existing patients in the file based on details of the patient's history, present illness, therapy to date, etc. It is to give meaningful access to accumulated experience to the young inexperienced therapists while providing an unbiased aid to be evaluated. As a start, Breast Cancer and its Radiation Therapy, as codified in the New England Medical Center Hospital's protocol will be used as a model.